DM1 Pt2-3 Pharmacology of Premedication Drugs Flashcards
(24 cards)
Does acepromazine provide analgesia?
Acepromazine provides sedation but is not generally considered to provide analgesia, although some data suggest it may in cats.
What are the cardiovascular effects of acepromazine?
Acepromazine causes vasodilation, which can lead to hypotension, especially in cats with cardiovascular disease or hypotension.
Why is acepromazine usually avoided in ASA 4 and 5 cats?
Due to its vasodilatory effects, it can cause marked hypotension in severely compromised cats.
What are the key effects of alpha 2 agonists like dexmedetomidine?
Alpha 2 agonists provide dose-dependent sedation and analgesia but have profound cardiovascular effects like reduced heart rate and cardiac output.
How does dexmedetomidine affect blood pressure?
It causes an initial increase in blood pressure due to vasoconstriction, followed by a return to normal levels after 20-30 minutes.
What is the main advantage of dexmedetomidine over medetomidine?
Dexmedetomidine is more specific for the alpha 2 receptor and does not require levomedetomidine, potentially reducing biological load.
How does dexmedetomidine reduce the need for other anaesthetic drugs?
It significantly reduces the dose of induction and maintenance agents like propofol, lowering drug concentrations by up to 50%.
What is the benefit of using atipamezole with dexmedetomidine?
Atipamezole reverses the effects of dexmedetomidine, reducing recovery time, but also reverses its analgesic effects, requiring other analgesics.
Why must anaesthetic agents be administered slowly after dexmedetomidine?
Dexmedetomidine slows blood-brain circulation, increasing the time to peak effect and raising the risk of anaesthetic overdose if not administered carefully.
Why should dexmedetomidine be avoided in cats with cardiovascular disease?
It reduces cardiac output, and cats with cardiovascular disease have reduced cardiac reserve, leading to poor organ perfusion and arrhythmias.
Why is dexmedetomidine not recommended for geriatric cats?
Geriatric cats have reduced cardiovascular reserve, making them more vulnerable to the effects of dexmedetomidine on cardiac output.
Why should dexmedetomidine be avoided in cats with liver disease?
It decreases liver blood flow, which can further compromise liver function.
In which cats is vomiting after dexmedetomidine undesirable?
Cats with raised intraocular or intracranial pressure, or those with a gastrointestinal foreign body, should avoid dexmedetomidine due to its emetic effect.
Why should dexmedetomidine be avoided in cats with severe systemic disease (ASA 3 or higher)?
Cats with severe systemic disease have reduced compensatory mechanisms to maintain cardiac output under the effects of dexmedetomidine.
What are the differences between diazepam and midazolam?
Diazepam can cause thrombophlebitis, has active metabolites, and longer duration, while midazolam is water-soluble, shorter-acting, and less painful to inject.
Why are benzodiazepines combined with ketamine for sedation in cats?
Benzodiazepines alone can cause excitation in healthy adult cats, but when combined with ketamine, they produce reliable sedation.
Why is ketamine always co-administered with another sedative?
Ketamine can cause central nervous system excitation when administered alone, so it’s combined with sedatives like dexmedetomidine or midazolam.
How does ketamine affect the cardiovascular system?
Ketamine is generally cardiovascularly stable, mildly stimulating the sympathetic nervous system, but it can cause myocardial depression in sick cats.
In which cats should ketamine be avoided?
Ketamine should be avoided in cats with hypertrophic cardiomyopathy, as it can increase heart rate and exacerbate myocardial oxygen imbalance.
What is alfaxalone used for in premedication?
Alfaxalone is used in anxious cats needing heavy sedation, especially when ketamine or dexmedetomidine is unsuitable, but it causes short-duration cardiovascular and respiratory depression.
Why should buprenorphine not be administered subcutaneously in cats?
Absorption from the subcutaneous route is slow, reducing its analgesic efficacy.
Which opioid is recommended for more invasive procedures in cats?
Methadone, a full µ opioid agonist, is recommended for more invasive procedures like limb amputation or exploratory laparotomy.
Why is pethidine not ideal for premedication in cats?
Pethidine is short-acting (90 minutes), requires large volumes for IM injection, and cannot be given IV due to histamine release.
Why is fentanyl unsuitable for premedication in most cats?
Fentanyl is very short-acting (20 minutes after IV administration), but can be combined with midazolam for haemodynamic stability in ASA 4 or 5 cats.
